A door hinge for concealed installation between a door frame and a door typically has a first and a second leaf assembly fittable into respective mortises in the edge of the door and in the door frame. At least the first leaf assembly has a body and mounting tabs that secure it to the door or frame and are provided at ends of the body. This body is adjustable relative to the mounting tabs. A two-part swivel mechanism connects the leaf assemblies.
Such a door hinge for concealed installation between a door frame and a wing of a door is known from EP 1 780 357. Each leaf assembly has a body and two mounting tabs at ends of the body. The mounting tabs each comprise a front plate and a rear plate. On one of the leaf assemblies the body is adjustable vertically relative to the leaf assemblies, screws engaging into elongated holes in the body to connect the front plate to the rear plate at the mounting tabs. With the screws removed the body can be displaced vertically and may be fixed in the desired position by firmly resecuring the screws. In order to avoid subsequent slipping of the body the rear sides of the front plates and the confronting faces of the body have ridges. On the other leaf assembly the mounting tabs each have an adjustment screw that extends between the front plate and the rear plate and by means of which the body may be positioned orthogonally and horizontally relative to the front face of the leaf assembly. This way, lateral displacement of the door within the door frame is possible by operation of the adjustment screw. In this context side-to-side displacement means that the door can be adjusted in a horizontal direction extending parallel to the closed door. The door hinge further has a swivel mechanism comprising two members that are pivoted on each other at a vertical pivot axis. The members are each pivoted in a respective one of the bodies, and are guided in a displaceable manner in sliding guides at their other ends.
Further such door hinges, in which at least one of the leaf assemblies has a body and mounting tabs for mounting on a door or on a door frame, are also known from DE 20 2005 018 102 and DE 20 2006 004 198.
A door hinge is known from US 2003/0088943 that is mounted concealed between the door frame and the door. In addition to two leaf assemblies and a hinge-bracket arrangement, the door hinge described therein also comprises inserts secured in mounting locations. To this end according to the invention the inserts are vertically and/or horizontally adjustable. A complete adjustment of the door requires two horizontal adjustment directions and one vertical adjustment direction. Adjustment in the three axes enables a sufficiently accurate alignment of the door relative to the door frame when mounting the door to the door frame, that is to center the door in the frame and set it flush to the frame. The alignment should be carried out with regard to the height and in a side-to-side direction with the door closed and parallel to a direction extending parallel to the door, and in a direction extending perpendicular to the closed door. According to US 2003/0088943, horizontal adjusters are provided on both leaf assemblies such that the adjustment of the door with regard to the door frame must be carried out on both leaf assemblies. With an opening angle of the inserted but not yet adjusted door of about 90° the adjustment of the adjusting paths for the adjustment in the one horizontal direction and in the other horizontal direction are additive, thus significantly complicating the installation, especially for the layperson. A further embodiment according to US 2003/0088943 provides the inserts on one of the leaf assemblies in two horizontal directions. Such an embodiment facilitating adjustment is extremely complex. Furthermore, the capacity of the door hinge is further limited by providing a second horizontally adjustable embodiment of the inserts.